In honor of Groundhog Day, we present a post about something that seems to happen every year: new research showing warming is unnatural and extreme.
A new study in Nature, covered in an Ars Technica story published Wednesday by Scott Johnson, once again confirms that humanity is warming the climate to a degree likely not reached in at least the past 11,000 years. The study, which uses pollen records from a variety of species from North America and Europe as a proxy for past temperatures, also shows that in the absence of human activity, natural cycles would be pushing temperatures down, not up.
Because this paper builds on the works of Mann and Marcott in determining just how unusual the current warming trend is compared to the natural cycles of the past, it will likely be a target for deniers. But odds are denier criticisms will be just as well-developed as their integrity.
Though there will likely be more attacks as others catch wind of the study, a brief post at WUWT gives a hint at the creative and specific criticisms deniers are sure to level against the study. In one of the few lines of commentary, WUWT regular David Middleton claims “climate models can’t adequately simulate the present-day climate.” Throwing out the entire climate modeling community is certainly a comprehensive response, if not particularly well tailored to the specifics of the study.
In terms of predicting legitimate criticisms, we do notice that the study only looks at temperatures in the Northern Hemisphere, and only uses one type of proxy- pollen. It’s not exactly the sort of comprehensive reconstruction like the PAGES 2k project. But by focusing so closely on Northern Hemisphere pollen records, this study able to provide a more nuanced result.
As Johnson explained in his piece, other reconstructions have some differences that likely result from different changes in summer (slight cooling) than during winter (strong warming trend). But this study compares pollen records of different species of plants, and in doing so is able to tease out the extent to which the winter warming trend offsets a slightly cooling summer trend.
Piece by piece, scientists are bringing the past temperatures into focus. Science is slow though, this study was in the works for five years. It takes a long time to analyze proxies, so if you’re eager for answers just be patient. We’ll get them, pollen good time, friends.
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